Java（8题）：异常，通过try catch进行处理，登录，商品，使用jdbc进行读取，详细图析
1.要求输入班级人数，人数必须是正整数。通过异常机制来处理下，提示输入的人数不能为负数
package a;
import java.util.Scanner;
public class yichang {
public static void main(String[] args) {
try {
System.out.println("请输入班级的人数");
Scanner s = new Scanner(System.in);
int renshu = s.nextInt();
if (renshu < 0) {
throw new RuntimeException("人数必须为正整数");
}
System.out.println("班级人数为" + renshu);
} catch (RuntimeException e) {
System.out.println("输入的人数不能为负数");
}
}
}
2.定义一个数组长度为3的数组，打印其数据，要求（使用异常制作）
package a;
public class yichang {
public static void main(String[] args) {
try {
int[] up=new int[3];
int num1=10;
int num2=1;
int num3=num1/num2;//除数为0的异常
up[0]=11;
up[1]=22;
up[2]=33;
up[3]=44;//下标越界的异常
} catch (ArithmeticException e) {
//出现除数为0的时候执行这块的内容
//除数为的操作
System. out. println("b站up主诗书画唱提醒你，你的除数为0啦，快点赞！");
}catch(ArrayIndexOutOfBoundsException e1){
//下标越界操作
System. out. println("b站up主诗书画唱提醒你，下标越界啦，快投币！");
}
catch(Exception e2){
//其他异常
System. out. println( "b站up主诗书画唱提醒你，出现了其他类型的异常，快三连，关注！");
}
}
}
3、创建Student对象，设置name和age属性,在main方法中添加如下的代码：
Student stu = null;
stu.setName("张三");
System.out.println("学生的姓名设置完毕");
4.请分析以上的代码出现的错误，并通过try catch进行处理。
package a;
public class yichang {
public static void main(String[] args) {
try {
Student stu=null;
stu. setName("张三");
System . out. println("诗书画唱提醒你，学生的姓名设置完毕");
} catch (Exception e) {
// TODO: handle exception
System. out. println("诗书画唱提醒你，学生的姓名设置有误");
}
}
class Student{
private String name;
private int age;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
}}
5.定义人的年龄不能大于100岁并小于1岁（使用异常制作）
package a;
import java.util.Scanner;
public class yichang {
public static void main(String[] args) {
try {System.out.println("请输入年龄");
Scanner s=new Scanner(System.in);//声明Scanner接收的类
int age= s.nextInt();//接收用户输入整形的数据
if(100<age||age<1){throw new Exception();
}
else{System . out. println("诗书画唱提醒你，人的年龄设置完毕");}
} catch (Exception e) {
// TODO: handle exception
System. out. println("诗书画唱提醒你，人的年龄不能大于100岁并不能小于1岁");
}
}
class shangpin{
private String name;
private int age;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age =age;
}
}}
//6.制作登录界面，使用异常判断用户输入是否为空，输入内容长度是否大于6位数，密码是否为空，年龄是否满18（使用异常制作）
package a;
import java.util.Scanner;
public class yichang {
public static void main(String[] args) {
che timegame = new huoche(1, "时间游戏", 30, 0, 3);
che mengame = new huoche(2, "爷们游戏", 50, 0, 5);
che woman= new keche(3, "女人游戏", 40, 4, 0);
che run = new keche(4, "跑步游戏", 80, 10, 0);
che swim = new pika(5, "游泳游戏", 60, 2, 4);
che sing = new pika(6, "唱歌游戏", 100, 4, 8);
che[] c = new che[6];
c[0] = timegame;
c[1] = mengame;
c[2] = woman;
c[3] = run;
c[4] = swim;
c[5] = sing;
yonghu yh = new yonghu();
che[] c_zuche = null;
while (true) {
System.out.println("---------“诗书画唱”名品牌游戏购买系统-----------");
System.out.println("请输入你的操作:1.登录 2.注册 3.跳出系统");
Scanner s = new Scanner(System.in);
int num = s.nextInt();
if (num == 1) {
System.out.println("----执行登录操作----");
System.out.println("请输入用户名:");
String uname = s.next();
try{
if(uname.length()<6){throw new StringIndexOutOfBoundsException("诗书画唱提醒你，"
+ "输入内容长度已经小于6");
/*拋出异常*/
}
else{System . out. println("输入内容长度已经不小于6");
}
} catch (StringIndexOutOfBoundsException e) {
// TODO: handle exception
System. out. println("诗书画唱提醒你，输入内容长度已经小于6，为确保你的安全，"
+ "最好大于6位数！且密码不能为空！");
}
System.out.println("请输入你的密码");
String pwd = s.next();
System.out.println("请输入你的年龄");
int age = s.nextInt();
if (uname.equals(yh.uname) && pwd.equals(yh.pwd)&& age ==yh.age) {
System.out.println("登录成功!");
break;
} else {
System.out.println("登录失败");
}
} else if (num == 2) {
System.out.println("----执行注册操作----");
System.out.println("请输入用户名:");
String uname = s.next();
System.out.println("请输入你的年龄");
int age = s.nextInt();
try{
if(age<18){throw new Exception("诗书画唱提醒你，你未满18岁，不能玩和购买这款游戏！");
}else{System . out. println("诗书画唱提醒你，年龄设置成功！");}
}
catch (Exception e) {
// TODO: handle exception
System. out. println("诗书画唱警告你，你未满18岁！");
}
System.out.println("请输入你的密码（最好输入内容长度大于6位数，不能为空）");
String pwd = s.next();
//pwd=null;
try{
if(pwd.length()<6){throw new StringIndexOutOfBoundsException("诗书画唱提醒你，密码不能小于6位数！");
/*拋出异常*/
}
else{System . out. println("诗书画唱提醒你，密码设置成功！");}
} catch (StringIndexOutOfBoundsException e) {
// TODO: handle exception
System. out. println("诗书画唱提醒你，输入内容长度不大于6位数，为确保你的安全，"
+ "必须大于6位数！且密码不能为空！");
}
catch (NullPointerException e) {
// TODO: handle exception
System. out. println("诗书画唱提醒你，密码不能为空！");
}
System.out.println("因为国家法律，要实名认证，请输入你的真实姓名");
String name = s.next();
yh.uname = uname;
yh.pwd = pwd;
yh.name = name;
yh.age = age;
System.out.println("注册成功!");
} else if (num == 3) {
System.exit(0);
}
}
// 购买游戏操作
while (true) {
System.out.println("欢迎," + yh.name + "请选择你的操作:");
System.out
.println("1.查看游戏列表 2.进行购买 3.查看我的购买总价格，总可在线玩人数，总可下线玩人数 4.跳出系统");
Scanner s1 = new Scanner(System.in);
int num = s1.nextInt();
if (num == 1) {
for (che i : c) {/* 相当于for(int i=0；i<c.length；i++) */
i.jieshao();
}
} else if (num == 2) {
System.out.println("请输入你要买的游戏数");
int num1 = s1.nextInt();
c_zuche = new che[num1];
for (int i = 0; i < num1; i++) {
System.out.println("请输入第" + (i + 1) + "游戏的编号");
int bianhao = s1.nextInt();
switch (bianhao) {
case 1:
c_zuche[i] = timegame;
break;
case 2:
c_zuche[i] = mengame;
break;
case 3:
c_zuche[i] = woman;
break;
case 4:
c_zuche[i] = run;
break;
case 5:
c_zuche[i] = swim;
break;
case 6:
c_zuche[i] = sing;
break;
}
}
System.out.println("购买成功!");
} else if (num == 3) {
if (c_zuche == null) {
System.out.println("你还没有进行购买呢！");
} else {
int zongjiage = 0;
int zongkezaixianwanrenshu = 0;
int zongkexiaxianwanrenshu = 0;
for (che i : c_zuche) {
i.jieshao();
zongjiage += i.jiage;
zongkezaixianwanrenshu += i.zaikeliang;
zongkexiaxianwanrenshu += i.zaiwuliang;
}
System.out.println("总价格" + zongjiage + "总可在线玩人数" +
zongkezaixianwanrenshu + "总可下线玩人数" + zongkexiaxianwanrenshu);
}
} else {
System.exit(0);/* 终止系统，不可为break，break是跳出循环 */
}
}
}
}
class yonghu {
String uname;
String pwd;
String name;
int age;
}
abstract class che {
int bianhao;
String name;
int jiage;
int zaikeliang;
int zaiwuliang;
public che(int bianhao, String name, int jiage, int zaikeliang,int zaiwuliang) {
this.bianhao = bianhao;
this.name = name;
this.jiage = jiage;
this.zaikeliang = zaikeliang;
this.zaiwuliang = zaiwuliang;
}
abstract void jieshao();
}
class huoche extends che {
public huoche(int bianhao, String name, int jiage,
int zaikeliang, int zaiwuliang) {
super(bianhao, name, jiage, zaikeliang, zaiwuliang);
}
void jieshao() {
System.out.println("编号" + this.bianhao + "\t名称:" + this.name +
"\t价格" + this.jiage + "\t总可在线玩人数" + this.zaiwuliang);
}
}
class keche extends che {
public keche(int bianhao, String name, int jiage, int zaikeliang,
int zaiwuliang) {
super(bianhao, name, jiage, zaikeliang, zaiwuliang);
}
void jieshao() {
System.out.println("编号" + this.bianhao + "\t名称:" +
this.name + "\t价格" + this.jiage + "\t总可下线玩人数" + this.zaikeliang);
}
}
class pika extends che {
public pika(int bianhao, String name, int jiage, int zaikeliang,
int zaiwuliang) {
super(bianhao, name, jiage, zaikeliang, zaiwuliang);
}
void jieshao() {
System.out.println("编号" + this.bianhao + "\t名称:" +
this.name + "\t价格" + this.jiage + "\t总可在线玩人数" + this.zaikeliang + "总可下线玩人数" +
this.zaiwuliang);
}
}
7.定义商品类，判断商品的价格是否大于100并小于500（使用异常制作）
package a;
import java.util.Scanner;
public class yichang {
public static void main(String[] args) {
try {System.out.println("请输入商品的价格");
Scanner s=new Scanner(System.in);//声明Scanner接收的类
int jiage= s.nextInt();//接收用户输入整形的数据
if(500<jiage||jiage<100){throw new Exception();
}
else{System. out. println("诗书画唱提醒你，商品的价格大于100并小于500");}
} catch (Exception e) {
// TODO: handle exception
System. out. println("诗书画唱提醒你，商品的价格不大于100并且不小于500");
}
}
class shangpin{
private String name;
private int jiage;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getJiage() {
return jiage;
}
public void setJiage(int jiage) {
this.jiage =jiage;
}
}}
//JDBC作业:
//1.建立一张数据库表stu，包含编号，姓名，年龄，性别，成绩属性，使用jdbc进行读取数据库中的数据
package a;
import java.sql.*;
public class yichang {
public static void main(String[] args) {
// TODO Auto-generated method stub
//Jar:各个数据库厂商都实现了ODBC规范，形成了自己的API,就是我们导入的这个jar包
// 1.加载数据库驱动(非运行时的异常)
try {
Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
// 2.建立连接(参数三个,1用户名 2密码 3数据库名称)
//这个链接数据库也要抛异常，为了方便，我将所有异常一块抛出
Connection con=DriverManager.getConnection("jdbc:sqlserver://DESKTOP-49FTFSP;"
+ "databaseName=stud","sa","1234abcd");
// 3.执行SQL语句
String sql="select * from Student";
Statement sta=con.createStatement();
// 4.获取结果(存入到数据连接池中)
ResultSet res=sta.executeQuery(sql);
// 5.遍历结果
while(res.next()){
System.out.print(res.getObject("Id")+" ");
System.out.print(res.getObject("Name")+" ");
System.out.print(res.getObject("Gender")+" ");
System.out.print(res.getObject("Height")+" ");
System.out.print(res.getObject("Weight")+" ");
System.out.print(res.getObject("Age")+" ");
System.out.print(res.getObject("Class")+" ");
System.out.println();
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
类比替换法。
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